I'm building a system that contains several chips (Intel 8085, 4 shift registers, SRAM, 8255 I/O) all connected to a common address and data bus. The highest frequency signals in the circuit are on the 8 MHz SPI bus used by the PIC18 monitor to shift bits (address or data) into and out of the SIPO and PISO registers. The frequency is that high because I want to capture all 8085 bus activity if possible. The next frequency is the 500 kHz (at most) parallel A/D bus.
I just began component placing and routing in Eagle and I've found the task daunting. So challenging that I'm considering scrapping the PCB and completing the entire circuit on a large breadboard, especially considering the fact that the only PCB I've ever designed is a 6x4 keypad in KiCAD which is nothing compared to a system of this complexity. I can't afford to spend a week patiently designing, wait weeks for the board to arrive, solder costly components only to have the board not work. I know mentioning deadlines here isn't cool but I do have a deadline in 3 weeks.
I've asked a question related to this issue before and Chris Stratton said that crosstalk is an issue mostly in theory (also use short wires, bypass, etc) but what I'm looking for some confirmation ("Yes its very doable though...") or a definite no-no ("You can't do it. Go play with something else."). Specifically,
- Has anyone else here designed something similar on a breadboard and it worked without glitches? No tricks to it but keep the wires as short as possible and bypass power on every rail?
- What are the odds that someone inexperienced in PCB design could design such a circuit well enough for it to work perfectly the first time after fabrication (at some fab house)? That is, barring any issues with code.
I would test this myself with a breadboard but I'm just about to order the final components needed for breadboard testing or those needed for the final PCB (IC sockets and the like). Which ones I purchase depend on the answers I get from you guys.